1. Field of the Invention
The present invention relates to a heat dissipating device, and more particularly to a heat dissipating device incorporating heat pipes to improve heat dissipation efficiency of a heat sink thereof.
2. Description of Related Art
Computer electronic devices such as central processing units (CPUs) are the core administrator of electrical signals in most contemporary personal computers. Continued development of CPUs has enabled them to perform more and more functions. Heat generated by CPUs has increased commensurately. Such heat can adversely affect the operational stability of computers. Measures must be taken to efficiently remove the heat from the CPUs. Typically, a heat sink is mounted on a CPU to remove heat therefrom.
Conventionally, a heat sink is made of high thermal conductivity metal materials and generally includes a base and a plurality of fins extending therefrom. The base contacts with an electronic device to absorb heat generated by the electronic device and conducts the heat to the fins, and further such heat is emitted to atmosphere. In order to improve heat-dissipating efficiency, a fan is often attached to a top of the fins to provide forced airflow. However, because of the resistance of the metal materials, a majority of the heat accumulates in the vicinity of the base of the heat sink and only a minority portion of that is conducted to the top of the fins. Thus, the heat sink has a disadvantage that the heat cannot be quickly transferred to the top of the heat sink, thereby reducing heat dissipation efficiency of the heat sink.
Currently, heat dissipating devices using heat pipes are broadly used, as the heat pipe possesses an extraordinary heat transfer capacity with almost no heat loss and can quickly transfer heat from one point to another. A heat pipe consists of a sealed aluminum or copper container with the internal walls lined with a capillary wick structure that is saturated with a working fluid. The most common types of wicks that are used are sintered powder, grooved tube and screen mesh. As the heat pipe absorbs heat at one end thereof, fluid is vaporized, and a pressure gradient is formed in the pipe. This pressure gradient forces the vapor to flow along the pipe from the one end to the other end where the vapor condenses and gives out its latent heat of vaporization. The working fluid is then returned back to the one end of the pipe via the capillary forces developed in the wick structure.
One kind of heat dissipating device using heat pipe has been devised to overcome the above-described disadvantage. As shown in Taiwan Patent Application No. 091212183, the heat dissipating device comprises two heat pipes and two heat sinks. Each heat sink has a base and a plurality fins from the base. The heat pipes are U-shaped. The two heat sinks are placed face to face, and are secured together via the heat pipes inserting into the bases of the two heat sinks. Thus, the heat can be dissipated more efficiently as the heat can be quickly transferred to the top of the heat sink via the heat pipes. Unfortunately, the heat cannot be quickly transferred to the top of the fins of each heat sink which will partially reduce the heat-dissipating efficiency of each heat sink. Thus, this kind of heat dissipating device needs to be improved.